The first castle on this important site where the London Road crosses the River Medway was built by Odo, the half-brother of William the Conqueror shortly after their victory in 1066. In 1088, following Williams death, Odo supported the King’s eldest son Robert for the crown and the castle was besieged by forces supporting the eventually successful son William Rufus. Records show that the following year repairs were made to the castle by Gandalf, Bishop of Rochester. The tower keep, much as it is seen today, was built in 1127 by William, Archbishop of Canterbury, who had come into possession of the castle.
In 1215 the castle was taken by the rebel barons and was subsequently besieged by the forces of King John. The defenders held out for two months but eventually, starving, they had to surrender the castle. It was besieged again in 1264, this time holding for the King against rebel barons although the outcome was different as the castle was relieved after a week by Royal forces.
In 1381 the castle was captured and ransacked during the peasant’s revolt. It was badly damaged and this seems to have made it turning point in the castle’s history as although repairs were carried out and people continued to live in the keep, the records show that the amount of repair work done was insufficient to keep the castle in a fully functional state and eventually it fell out of use. Much of the stone from the external walls and outbuildings was carried away and used on other building projects such as nearby Upnor Castle.
In 1870, the site was opened as a public park and eventually passed into the hands of the local authority, then the ministry of public works and finally to English Heritage.